When conventional pneumatic tires of the type used on automobiles, trucks, and the like are damaged, by a puncture or the like, so that they lose pressure and collapse, the vehicle is unable to continue and the tire must be repaired or replaced before driving can continue. This is both inconvenient and dangerous as tire failures often result in the loss of vehicle control, serious injuries, and fatalities. A tire failure in busy traffic or a hostile environment can also be dangerous. In some situations, such as for security vehicles and military applications, it may be very dangerous.
In the past, two solutions have been proposed to allow at least limited continued driving of a vehicle after a tire loses inflation. One of these employs self-supporting tires which have stiffer, heavier reinforced sidewalls than conventional tires, which temporarily support the weight of the vehicle when air pressure is lost. Alternatively, tires may use an auxiliary support ring attached to the wheel that will temporarily support the weight of the vehicle.
While these run-flat tires are currently used for specialty application vehicles, such as military, armored cars, emergency, and NASCAR vehicles, their adoption as a mainstream replacement for conventional tires has not occurred for a number of reasons. To incorporate the run-flat support, several key performance features are compromised. These include poor ride, poor handling, poor traction, lower fuel economy, lower life, higher cost, and difficulty of servicing of previous run-flat tires. The previous designs only provide for operating the vehicle on a flat tire rather than reestablishing full support for the tire so that it and the vehicle can, without interruption, resume normal operation.
Underinflated tires are a major cause of tire failure. Automatic tire inflation systems are desirable for maintaining proper tire pressures, preventing tire failures, extending tire life, and maintaining tire performance for safe operation. While tire pressure monitoring systems have been adopted for mainstream use on certain vehicles, the automatic tire inflation systems have not been adopted for mainstream use as they are complicated, expensive, and difficult to service.